##############################################

• if…then
• if…then…else
• if…then…elif
• for…in
• for
• while
• until
• break and continue
• case
• select
• exec
• Interrupt processing (SIGNAL)
• Functions()


##############################################

if [[ string/numeric expression ]]

then

	command(s)

elif [[ string/numeric expression ]]

	command(s)

else

	command(s)

fi

##############################################

if (( numeric expression ))	

then

	command(s)

elif [[ string/numeric expression ]]

	command(s)

else

	command(s)

fi

##############################################

for _variable in list

do

	command(s)

done

##############################################

for _IPS in `dig google.com | grep -v ';' | sed '1d' | awk '{print $5}' | uniq`; do ping $_IPS; done

##############################################

while command

do
	command(s)	

done

##############################################

#!/usr/bin/bash

clear;

echo -n "whic rock group is my fovarite?"

read _ANSWER

while [[ $_ANSWER != @(kiss||Kiss) ]]

do

	echo -n "No, try again: "

	read _ANSWER

done

	echo "You got it !!!"
exit

##############################################

#!/bin/bash

echo -n "whic rock group is my fovarite?"

read _ANSWER

until [[ $_ANSWER == @(kiss||Kiss) ]]

do

    echo -n "No, try again: "

    read _ANSWER

done

    echo "You got it !!!"

exit

##############################################

select var in wordlist

do
	command(s)	

done

##############################################

#!/usr/bin/bash

PS3="Select a day (1-4): "

select i in mon tue wed exit
do
  case $i in
    mon) echo "Monday";;
    tue) echo "Tuesday";;
    wed) echo "Wednesday";;
    exit) exit;;
  esac
done


##############################################

#!/usr/bin/bash

PS3="Select a program to run: "

select _PROGRAM in 'ls -aih' uptime last who exit

do

	$_PROGRAM

done

##############################################

case variable in

	value1)

		command(s)
		;;
	value2)

		command(s)
		;;
	value3)

		command(s)
		;;
	value4)

		command(s)
		;;
	value*)

		command(s)
		;;
esac



##############################################

:- 	if its not have a value, one time only set substitution
:=	if its not have a value, permenantly set avalue
:?	if its not have a value, print the error message. if its have then print it. 
:+	if its have a value, one time only set substitution

##############################################
String Test

[ string1 = string2 ] 		st1 is the same st2
[ string1 == string2 ] 		same as above
[ string1 != string2 ] 		st1 is NOT the same st2
[ string1 ] 			    st1 is NOT NULL - simply tests to see if string exists
[ -n string1 ] 			    test to see if string length is NON-zero
[ -z string1 ] 			    test to see if string length is IS zero
[ -l string1 ] 			    test to see what the length of the st1 is in characters

Logical String Test

[ string1 -a string2 ] 		test to see if BOTH st1 AND st2 are true
[ string1 -o string2 ] 		test to see if EITHER st1 OR st2 are true
[ ! string1 ] 			    does NOT match st1

Logical Compound Testing

[[ pattern1 && pattern2 ]]	BOTH ptrn1 AND ptrn2 are true
[[ pattern1 || pattern2 ]]	EITHER ptrn1 OR ptrn2 is true
[[ ! pattern1 ]]		    does NOT match ptrn1

Integer Test

[ int1 -eq int2 ]		    int1 is EQUAL to int2

-ne NOT equal
-gt greater than
-lt less than
-ge greater equal
-le less equal

Binary Operators for Files

[ file1 -nt file2 ] 		true if  file1 is newer than file2 (per the modification date)
[ file1 -ot file2 ] 		true if  file1 is older than file2 (per the modification date)
[ file1 -ef file2 ] 		true if  file1 and file2 have the same device or inode number (hard link)

File Testing Operators

 TEST		|	TEST is TRUE if...
----------------------------------
-b filename		the file is a BLOCK file
-x filename		the file is an EXECUTABLE file
-c filename		the file is a CHARACTER file
-w filename		the file is a WRITEABLE file
-d filename		the file is a DIRECTORY file
-u filename		the file has the SET-USER-ID bit on
-e filename		the file exist
-t filename		the fd (file descriptor) is opened on a terminal
-f filename		the file is a REGULAR file and it exists
-s filename		the file is a NON-ZERO in size
-S filename		the file is a SOKET file
-g filename		the file has the SET-GROUP-ID is set
-G filename		the file exists AND is owned by the effective GROUP ID
-r filename		the file is READABLE
-k filename		the file has the STICKY BIT is set
-l filename		the file is a SYMBOLINK LINK
-p filename		the file is a NAMED PIPE
-O filename		the file exists AND is owned by the effective USER ID

##############################################

Expect

spawn
expect
send
interact


##############################################

A; B    	Run A and then B, regardless of success of A
A && B  	Run B if A succeeded
A || B  	Run B if A failed
A &     	Run A in background.
A & B & 	Run A in background, then run B in background (regardless of success)
(A; B)		Run A and then B, regardless of A stop.